OST File Size Limit

How to configure OST file size limit with ease?

Depending upon your requirement, you may want to limit the OST file size so that it does not impact the performance of MS Outlook. For example, the best practice is to keep the ost file size maximum up to 1 GB. OST file of above 1 GB or more may cause problems like slow Outlook, increased the chance of corruption, etc. To avoid such issues, you can configure OST file size limit by making changes in the registry entries.

Like OST file, you can also limit PST file size so that it does cause any problem in the functioning of Microsoft Outlook. MS Outlook uses PST file to store users' emails in the lost data storage file called PST, and the OST file is used to store data when the user works in the offline mode. Let us see the process to configure OST file size limit with ease.

How to configure OST file size limit with ease?

In order to limit the OST fie size, there are two registry entries that need to be modified. Those registry entries are:

MaxFileSize registry entry: This registry entry helps you to specify the maximum file size that you want for the OST file. After reaching the maximum file size specified for the OST file, Outlook will not save further data in the OST file.

WarnFileSize registry entry: This registry entry helps you to specify the OST file size limit after which Outlook will generates a warning about the OST size limit. You will not be allowed to save more data in the same OST file.

What to do when OST file reaches the maximum file size limit?

When the OST file reaches the maximum file size limit specified in the registry entries, you suggest removing the emails and other data that is not important for you. By deleting that unwanted data, you will free space on the OST file, and then Outlook will allow you to save more data on the same OST file.

How to Locate Registry Entries to Limit OST File Size?

Given below are the locations of registry entries that you can modify:

Click the Microsoft Start button and the click RUN. Or, after clicking the Microsoft Start button, press CTRL + R. It will open the RUN window.

Type Regedit in the Run window and then click the OK You will see registry editor window

In the left-navigation panel, click My Computer and expand it.

Now, click HKEY_CURRENT_USER and expand it.

Now, click Software to expand it.

After this click Microsoft and expand it.

Now, click Office and expand it.

Click 11.0 if your version is Outlook 2003, 12.0 if your version is Outlook 2007, or 14.0 if your Outlook version is 2010.

Locate OST and click it. Upon clicking OST, you will see its related option in the right-panel.

Right-click MaxFileSize and select the Modify

Now, enter the maximum file size for the OST file in the Value data

Click the OK

This is how you can specify the Maximum file size limit for OST. Now, if you also want to specify a size for WarnFileSize key then repeat steps 10 to 12. This time you will have to right-click the WarnFileSize key instead of MaxFileSize. You can also configure the WarnFileSize registry entry.

In case, you have configured OST file size in the WarnFileSize and WarnFileSize registry keys then upon reaching the maximum file size, MS Outlook will activate the compact function so that the useless space can be utilized to reduce the OST file size. In case, you do not see any difference and Outlook does not save any data in the OST file then do not worry. Rather try to manually remove unwanted emails, attachments, sent items, drafts, etc to free the space.

What to do if Outlook OST is inaccessible?

Like other files, Outlook OST file is prone to corruption, and when it happens, MS Outlook gets failed to create a connection with it. In this situation, you may experience errors indicating the damage of the OST file. However, you need not worry about losing the emails and other data because you can easily use OST File repair software to repair the damaged OST file and recover data from it.